The present invention relates to a device for mounting an actuator. More particularly, it relates to a mounting device for facilitating rapid mounting of a direct coupled actuator used in conjunction with an air flow control device.
Electromechanical actuators, and in particular direct coupled actuators, have a wide variety of applications. Generally speaking, actuators receive a control signal and mechanically reposition a final control element in response to that control signal. For example, in the heating, ventilating and air conditioning (HVAC) industry, an actuator is commonly used to control positioning of a damper or other similar air flow control unit in response to a signaling device, such as a thermostat. The damper may be used to control building air flow, rooftop exhaust fans, supply fans, variable air volume equipment, internal exhaust systems, cooling towers, combustion air inlets for boilers or furnace rooms, steam, hot water or chilled water lines, to name but a few applications.
Regardless of the specific application, the damper (or similar air flow control unit) generally includes a damper blade linked to an output shaft. Movement of the output shaft dictates a position of the damper blade. Positioning of the damper blade, in turn, determines the volume, if any, of air flow through duct work or other structures associated with the damper blade. For example, rotation of the output shaft will cause the damper blade to move between an open position and a closed position. The actuator causes the desired movement by imparting a rotational (or moment) torque onto the output shaft which in turn applies a force onto the damper blade. The actuator itself is seldom an integral component of the damper. Instead, actuators with various types of power supplies and control inputs are available. Depending upon the particular application, an appropriate actuator is selected and installed.
In general terms, a damper control actuator includes an electronically controlled drive mechanism designed to maneuver the damper output shaft between an open and closed position. To this end, conventional (or foot mounted) actuators require the use of a rod-type linkage connected between the actuator drive and the output shaft. Recently, direct coupled actuators have been developed. Direct coupled actuators are typically installed directly on the damper output shaft, eliminating the need for an auxiliary linkage assembly. With this in mind, a direct coupled actuator normally includes an actuator housing maintaining a rotatable hub and a motor. The hub is sized to be mounted to the damper output shaft. The motor, in turn, is associated with the hub, imparting a torque or moment load on the hub, and thus on the output shaft.
During installation, the hub is mounted to the output shaft. The actuator housing, in turn, is then secured to a rigid support structure associated with the damper being controlled. For example, the actuator housing may be connected to duct work or a frame directly associated with the damper in question. Alternatively, the actuator housing may be mounted to any nearby support structure, including auxiliary ducts or frames, building ceilings or floors, furnace housing, cooling tower chassis, etc. Attachment of the actuator housing to a rigid support structure provides a resistance to the moment load generated by the motor. Normally, however, the output shaft is connected by additional linkages to the damper blade and operates such that the output shaft does not subject the actuator itself to any significant forces. In other words, the actuator is not required to support or provide a bearing position for the output shaft. The output shaft effectively isolates the actuator from any forces normal to the actuator housing. Thus, a single bolt securing the actuator housing to the rigid support structure is typically sufficient.
Notwithstanding the above description, certain air flow control configurations, do, in fact, rely upon the actuator to provide a bearing position for, and otherwise support, the output shaft. For example, the output shaft may be configured as a threaded rod to maintain the damper blade. With this arrangement, rotation of the output shaft causes the damper blade to maneuver along an axis of the output shaft. The actuator, in turn, is required to not only impart a rotational torque onto the output shaft, but also to support an axial position for, and resist axial movement of, the output shaft. In this regard, use of a single bolt to secure the actuator housing to the rigid support structure associated with the air flow control unit will not provide requisite support. The single bolt coupling will likely fail when a force or load normal to the actuator housing is generated by the output shaft. Additionally, even with xe2x80x9cstandardxe2x80x9d air flow control applications, the installer may desire to provide a more rigid connection between the actuator housing and the support structure in question.
One potential solution to the above-described installation issue is to use four or more bolts to secure the actuator housing to the rigid support structure. Unfortunately, this approach is relatively time consuming. Additionally, in light of the forces potentially placed upon the actuator housing, it may be that use of four or more bolts will not satisfy the force constraints placed on the actuator. Further, because the actuator housing and bolts are made of steel, any vibration of the actuator housing relative to the bolts will generate a substantial amount of noise.
Direct coupled actuators continue to be extremely popular commercial damper control devices. However, with certain applications, the generally accepted technique of mounting the actuator housing to a support structure with a single bolt may not provide a sufficiently rigid connection. Further, the use of additional bolts is time consuming and may not satisfy the output shaft positioning and load concerns presented by a particular application. Therefore, a need exists for an actuator mounting device for facilitating rapid mounting of the actuator and resulting in a more complete coupling between the actuator and the support structure associated with the air flow control unit.
One aspect of the present invention provides an actuator mounting device for mounting an actuator having an actuator housing to a support structure associated with a fluid flow control unit. The mounting device includes a mounting bracket and a pair of guide members. The mounting bracket includes a pair of spaced side walls, the rails and a stop. The pair of spaced side walls define a leading end and a trailing end. Further, each of the side walls has a base portion securable to a support structure associated with the fluid flow control unit. A separate one of the rails extends from each side wall. Finally, the stop is associated with the trailing end of the pair of spaced side walls. The pair of guide members are each mountable to an opposing side of an actuator housing. Each of the guide members includes a bearing surface configured to slidably engage a respective one of the rails. During assembly, the rails direct the actuator, via the guide members, to a secured position at which the stop limits further movement of the actuator housing. The sliding relationship between the guide members and rails facilitates rapid mounting of the actuator to the support structure. Further, in the secured position, the mounting device rigidly connects the actuator to the support structure via an interface between the rails and guide members.
Another aspect of the present invention provides an improved direct coupled actuator. The actuator includes an actuator housing maintaining a rotatable hub for connection to an output shaft of a fluid flow control unit and a motor for driving the hub. The actuator housing includes opposing sides. With this configuration in mind, the improvement comprises a first guide member mounted to a first one of the opposing sides, and a second guide member mounted to a second one of the opposing sides. Each of the guide members includes a pair of spaced legs defining an elongated slot. The elongated slot is configured to slidably engage a portion of a support structure associated with a fluid flow control unit. In this regard, the guide members facilitate rapid mounting of the actuator to the support structure via a sliding relationship. Additionally, upon final assembly, the guide members rigidly secure the actuator housing to the support structure such that the actuator housing supports forces generated by the output shaft.
Yet another aspect of the present invention relates to a method of mounting an actuator to a support structure associated with a fluid flow control unit. The actuator includes an actuator housing having opposing sides. The method includes securing a first guide member to a first one of the opposing sides. A second guide member is secured to a second one of the opposing sides. In this regard, each of the guide members provides an elongated engagement surface defined by a first end and a second end. A mounting bracket is attached to a support structure associated with a fluid flow control unit. The mounting bracket includes a pair of spaced side walls defining a leading end and a trailing end. A separate rail extends from each side wall. Finally, a stop is positioned adjacent the trailing end. The method includes positioning the actuator housing relative to the mounting bracket such that the first end of each of the engagement surfaces is aligned with a respective one of the rails at the leading end of the mounting bracket. The engagement surfaces are slid along the rails such that the first ends of the engagement surfaces are maneuvered toward the trailing end of the mounting bracket. As a result of this sliding motion, the actuator housing is directed into connection with the stop.